xref: /freebsd/sys/net/if_stf.c (revision 3193579b66fd7067f898dbc54bdea81a0e6f9bd0)
1 /*	$FreeBSD$	*/
2 /*	$KAME: if_stf.c,v 1.73 2001/12/03 11:08:30 keiichi Exp $	*/
3 
4 /*
5  * Copyright (C) 2000 WIDE Project.
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of the project nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 /*
34  * 6to4 interface, based on RFC3056.
35  *
36  * 6to4 interface is NOT capable of link-layer (I mean, IPv4) multicasting.
37  * There is no address mapping defined from IPv6 multicast address to IPv4
38  * address.  Therefore, we do not have IFF_MULTICAST on the interface.
39  *
40  * Due to the lack of address mapping for link-local addresses, we cannot
41  * throw packets toward link-local addresses (fe80::x).  Also, we cannot throw
42  * packets to link-local multicast addresses (ff02::x).
43  *
44  * Here are interesting symptoms due to the lack of link-local address:
45  *
46  * Unicast routing exchange:
47  * - RIPng: Impossible.  Uses link-local multicast packet toward ff02::9,
48  *   and link-local addresses as nexthop.
49  * - OSPFv6: Impossible.  OSPFv6 assumes that there's link-local address
50  *   assigned to the link, and makes use of them.  Also, HELLO packets use
51  *   link-local multicast addresses (ff02::5 and ff02::6).
52  * - BGP4+: Maybe.  You can only use global address as nexthop, and global
53  *   address as TCP endpoint address.
54  *
55  * Multicast routing protocols:
56  * - PIM: Hello packet cannot be used to discover adjacent PIM routers.
57  *   Adjacent PIM routers must be configured manually (is it really spec-wise
58  *   correct thing to do?).
59  *
60  * ICMPv6:
61  * - Redirects cannot be used due to the lack of link-local address.
62  *
63  * stf interface does not have, and will not need, a link-local address.
64  * It seems to have no real benefit and does not help the above symptoms much.
65  * Even if we assign link-locals to interface, we cannot really
66  * use link-local unicast/multicast on top of 6to4 cloud (since there's no
67  * encapsulation defined for link-local address), and the above analysis does
68  * not change.  RFC3056 does not mandate the assignment of link-local address
69  * either.
70  *
71  * 6to4 interface has security issues.  Refer to
72  * http://playground.iijlab.net/i-d/draft-itojun-ipv6-transition-abuse-00.txt
73  * for details.  The code tries to filter out some of malicious packets.
74  * Note that there is no way to be 100% secure.
75  */
76 
77 #include "opt_inet.h"
78 #include "opt_inet6.h"
79 #include "opt_mac.h"
80 
81 #include <sys/param.h>
82 #include <sys/systm.h>
83 #include <sys/socket.h>
84 #include <sys/sockio.h>
85 #include <sys/mac.h>
86 #include <sys/mbuf.h>
87 #include <sys/errno.h>
88 #include <sys/kernel.h>
89 #include <sys/protosw.h>
90 #include <sys/queue.h>
91 #include <machine/cpu.h>
92 
93 #include <sys/malloc.h>
94 
95 #include <net/if.h>
96 #include <net/route.h>
97 #include <net/netisr.h>
98 #include <net/if_types.h>
99 #include <net/if_stf.h>
100 
101 #include <netinet/in.h>
102 #include <netinet/in_systm.h>
103 #include <netinet/ip.h>
104 #include <netinet/ip_var.h>
105 #include <netinet/in_var.h>
106 
107 #include <netinet/ip6.h>
108 #include <netinet6/ip6_var.h>
109 #include <netinet6/in6_var.h>
110 #include <netinet/ip_ecn.h>
111 
112 #include <netinet/ip_encap.h>
113 
114 #include <machine/stdarg.h>
115 
116 #include <net/net_osdep.h>
117 
118 #include <net/bpf.h>
119 
120 #define STFNAME		"stf"
121 
122 #define IN6_IS_ADDR_6TO4(x)	(ntohs((x)->s6_addr16[0]) == 0x2002)
123 
124 /*
125  * XXX: Return a pointer with 16-bit aligned.  Don't cast it to
126  * struct in_addr *; use bcopy() instead.
127  */
128 #define GET_V4(x)	((caddr_t)(&(x)->s6_addr16[1]))
129 
130 struct stf_softc {
131 	struct ifnet	sc_if;	   /* common area */
132 	union {
133 		struct route  __sc_ro4;
134 		struct route_in6 __sc_ro6; /* just for safety */
135 	} __sc_ro46;
136 #define sc_ro	__sc_ro46.__sc_ro4
137 	const struct encaptab *encap_cookie;
138 	LIST_ENTRY(stf_softc) sc_list;	/* all stf's are linked */
139 };
140 
141 static LIST_HEAD(, stf_softc) stf_softc_list;
142 
143 static MALLOC_DEFINE(M_STF, STFNAME, "6to4 Tunnel Interface");
144 static int ip_stf_ttl = 40;
145 
146 extern  struct domain inetdomain;
147 struct protosw in_stf_protosw =
148 { SOCK_RAW,	&inetdomain,	IPPROTO_IPV6,	PR_ATOMIC|PR_ADDR,
149   in_stf_input,	(pr_output_t*)rip_output, 0,	rip_ctloutput,
150   0,
151   0,            0,              0,              0,
152   &rip_usrreqs
153 };
154 
155 static int stfmodevent(module_t, int, void *);
156 static int stf_encapcheck(const struct mbuf *, int, int, void *);
157 static struct in6_ifaddr *stf_getsrcifa6(struct ifnet *);
158 static int stf_output(struct ifnet *, struct mbuf *, struct sockaddr *,
159 	struct rtentry *);
160 static int isrfc1918addr(struct in_addr *);
161 static int stf_checkaddr4(struct stf_softc *, struct in_addr *,
162 	struct ifnet *);
163 static int stf_checkaddr6(struct stf_softc *, struct in6_addr *,
164 	struct ifnet *);
165 static void stf_rtrequest(int, struct rtentry *, struct rt_addrinfo *);
166 static int stf_ioctl(struct ifnet *, u_long, caddr_t);
167 
168 int	stf_clone_create(struct if_clone *, int);
169 void	stf_clone_destroy(struct ifnet *);
170 
171 /* only one clone is currently allowed */
172 struct if_clone stf_cloner =
173     IF_CLONE_INITIALIZER(STFNAME, stf_clone_create, stf_clone_destroy, 0, 0);
174 
175 int
176 stf_clone_create(ifc, unit)
177 	struct if_clone *ifc;
178 	int unit;
179 {
180 	struct stf_softc *sc;
181 
182 	sc = malloc(sizeof(struct stf_softc), M_STF, M_WAITOK | M_ZERO);
183 	if_initname(&sc->sc_if, ifc->ifc_name, unit);
184 
185 	sc->encap_cookie = encap_attach_func(AF_INET, IPPROTO_IPV6,
186 	    stf_encapcheck, &in_stf_protosw, sc);
187 	if (sc->encap_cookie == NULL) {
188 		printf("%s: attach failed\n", if_name(&sc->sc_if));
189 		free(sc, M_STF);
190 		return (ENOMEM);
191 	}
192 
193 	sc->sc_if.if_mtu    = IPV6_MMTU;
194 	sc->sc_if.if_ioctl  = stf_ioctl;
195 	sc->sc_if.if_output = stf_output;
196 	sc->sc_if.if_type   = IFT_STF;
197 	sc->sc_if.if_snd.ifq_maxlen = IFQ_MAXLEN;
198 	if_attach(&sc->sc_if);
199 	bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
200 	LIST_INSERT_HEAD(&stf_softc_list, sc, sc_list);
201 	return (0);
202 }
203 
204 void
205 stf_clone_destroy(ifp)
206 	struct ifnet *ifp;
207 {
208 	int err;
209 	struct stf_softc *sc = (void *) ifp;
210 
211 	LIST_REMOVE(sc, sc_list);
212 	err = encap_detach(sc->encap_cookie);
213 	KASSERT(err == 0, ("Unexpected error detaching encap_cookie"));
214 	bpfdetach(ifp);
215 	if_detach(ifp);
216 
217 	free(sc, M_STF);
218 }
219 
220 static int
221 stfmodevent(mod, type, data)
222 	module_t mod;
223 	int type;
224 	void *data;
225 {
226 
227 	switch (type) {
228 	case MOD_LOAD:
229 		LIST_INIT(&stf_softc_list);
230 		if_clone_attach(&stf_cloner);
231 
232 		break;
233 	case MOD_UNLOAD:
234 		if_clone_detach(&stf_cloner);
235 
236 		while (!LIST_EMPTY(&stf_softc_list))
237 			stf_clone_destroy(&LIST_FIRST(&stf_softc_list)->sc_if);
238 		break;
239 	}
240 
241 	return (0);
242 }
243 
244 static moduledata_t stf_mod = {
245 	"if_stf",
246 	stfmodevent,
247 	0
248 };
249 
250 DECLARE_MODULE(if_stf, stf_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
251 
252 static int
253 stf_encapcheck(m, off, proto, arg)
254 	const struct mbuf *m;
255 	int off;
256 	int proto;
257 	void *arg;
258 {
259 	struct ip ip;
260 	struct in6_ifaddr *ia6;
261 	struct stf_softc *sc;
262 	struct in_addr a, b, mask;
263 
264 	sc = (struct stf_softc *)arg;
265 	if (sc == NULL)
266 		return 0;
267 
268 	if ((sc->sc_if.if_flags & IFF_UP) == 0)
269 		return 0;
270 
271 	/* IFF_LINK0 means "no decapsulation" */
272 	if ((sc->sc_if.if_flags & IFF_LINK0) != 0)
273 		return 0;
274 
275 	if (proto != IPPROTO_IPV6)
276 		return 0;
277 
278 	/* LINTED const cast */
279 	m_copydata((struct mbuf *)(uintptr_t)m, 0, sizeof(ip), (caddr_t)&ip);
280 
281 	if (ip.ip_v != 4)
282 		return 0;
283 
284 	ia6 = stf_getsrcifa6(&sc->sc_if);
285 	if (ia6 == NULL)
286 		return 0;
287 
288 	/*
289 	 * check if IPv4 dst matches the IPv4 address derived from the
290 	 * local 6to4 address.
291 	 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
292 	 */
293 	if (bcmp(GET_V4(&ia6->ia_addr.sin6_addr), &ip.ip_dst,
294 	    sizeof(ip.ip_dst)) != 0)
295 		return 0;
296 
297 	/*
298 	 * check if IPv4 src matches the IPv4 address derived from the
299 	 * local 6to4 address masked by prefixmask.
300 	 * success on: src = 10.1.1.1, ia6->ia_addr = 2002:0a00:.../24
301 	 * fail on: src = 10.1.1.1, ia6->ia_addr = 2002:0b00:.../24
302 	 */
303 	bzero(&a, sizeof(a));
304 	bcopy(GET_V4(&ia6->ia_addr.sin6_addr), &a, sizeof(a));
305 	bcopy(GET_V4(&ia6->ia_prefixmask.sin6_addr), &mask, sizeof(mask));
306 	a.s_addr &= mask.s_addr;
307 	b = ip.ip_src;
308 	b.s_addr &= mask.s_addr;
309 	if (a.s_addr != b.s_addr)
310 		return 0;
311 
312 	/* stf interface makes single side match only */
313 	return 32;
314 }
315 
316 static struct in6_ifaddr *
317 stf_getsrcifa6(ifp)
318 	struct ifnet *ifp;
319 {
320 	struct ifaddr *ia;
321 	struct in_ifaddr *ia4;
322 	struct sockaddr_in6 *sin6;
323 	struct in_addr in;
324 
325 	for (ia = TAILQ_FIRST(&ifp->if_addrlist);
326 	     ia;
327 	     ia = TAILQ_NEXT(ia, ifa_list))
328 	{
329 		if (ia->ifa_addr == NULL)
330 			continue;
331 		if (ia->ifa_addr->sa_family != AF_INET6)
332 			continue;
333 		sin6 = (struct sockaddr_in6 *)ia->ifa_addr;
334 		if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr))
335 			continue;
336 
337 		bcopy(GET_V4(&sin6->sin6_addr), &in, sizeof(in));
338 		LIST_FOREACH(ia4, INADDR_HASH(in.s_addr), ia_hash)
339 			if (ia4->ia_addr.sin_addr.s_addr == in.s_addr)
340 				break;
341 		if (ia4 == NULL)
342 			continue;
343 
344 		return (struct in6_ifaddr *)ia;
345 	}
346 
347 	return NULL;
348 }
349 
350 static int
351 stf_output(ifp, m, dst, rt)
352 	struct ifnet *ifp;
353 	struct mbuf *m;
354 	struct sockaddr *dst;
355 	struct rtentry *rt;
356 {
357 	struct stf_softc *sc;
358 	struct sockaddr_in6 *dst6;
359 	struct in_addr in4;
360 	caddr_t ptr;
361 	struct sockaddr_in *dst4;
362 	u_int8_t tos;
363 	struct ip *ip;
364 	struct ip6_hdr *ip6;
365 	struct in6_ifaddr *ia6;
366 #ifdef MAC
367 	int error;
368 
369 	error = mac_check_ifnet_transmit(ifp, m);
370 	if (error) {
371 		m_freem(m);
372 		return (error);
373 	}
374 #endif
375 
376 	sc = (struct stf_softc*)ifp;
377 	dst6 = (struct sockaddr_in6 *)dst;
378 
379 	/* just in case */
380 	if ((ifp->if_flags & IFF_UP) == 0) {
381 		m_freem(m);
382 		ifp->if_oerrors++;
383 		return ENETDOWN;
384 	}
385 
386 	/*
387 	 * If we don't have an ip4 address that match my inner ip6 address,
388 	 * we shouldn't generate output.  Without this check, we'll end up
389 	 * using wrong IPv4 source.
390 	 */
391 	ia6 = stf_getsrcifa6(ifp);
392 	if (ia6 == NULL) {
393 		m_freem(m);
394 		ifp->if_oerrors++;
395 		return ENETDOWN;
396 	}
397 
398 	if (m->m_len < sizeof(*ip6)) {
399 		m = m_pullup(m, sizeof(*ip6));
400 		if (!m) {
401 			ifp->if_oerrors++;
402 			return ENOBUFS;
403 		}
404 	}
405 	ip6 = mtod(m, struct ip6_hdr *);
406 	tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
407 
408 	/*
409 	 * Pickup the right outer dst addr from the list of candidates.
410 	 * ip6_dst has priority as it may be able to give us shorter IPv4 hops.
411 	 */
412 	ptr = NULL;
413 	if (IN6_IS_ADDR_6TO4(&ip6->ip6_dst))
414 		ptr = GET_V4(&ip6->ip6_dst);
415 	else if (IN6_IS_ADDR_6TO4(&dst6->sin6_addr))
416 		ptr = GET_V4(&dst6->sin6_addr);
417 	else {
418 		m_freem(m);
419 		ifp->if_oerrors++;
420 		return ENETUNREACH;
421 	}
422 	bcopy(ptr, &in4, sizeof(in4));
423 
424 #if NBPFILTER > 0
425 	if (ifp->if_bpf) {
426 		/*
427 		 * We need to prepend the address family as
428 		 * a four byte field.  Cons up a dummy header
429 		 * to pacify bpf.  This is safe because bpf
430 		 * will only read from the mbuf (i.e., it won't
431 		 * try to free it or keep a pointer a to it).
432 		 */
433 		struct mbuf m0;
434 		u_int32_t af = AF_INET6;
435 
436 		m0.m_next = m;
437 		m0.m_len = 4;
438 		m0.m_data = (char *)&af;
439 
440 #ifdef HAVE_OLD_BPF
441 		BPF_MTAP(ifp, &m0);
442 #else
443 		bpf_mtap(ifp->if_bpf, &m0);
444 #endif
445 	}
446 #endif /*NBPFILTER > 0*/
447 
448 	M_PREPEND(m, sizeof(struct ip), M_DONTWAIT);
449 	if (m && m->m_len < sizeof(struct ip))
450 		m = m_pullup(m, sizeof(struct ip));
451 	if (m == NULL) {
452 		ifp->if_oerrors++;
453 		return ENOBUFS;
454 	}
455 	ip = mtod(m, struct ip *);
456 
457 	bzero(ip, sizeof(*ip));
458 
459 	bcopy(GET_V4(&((struct sockaddr_in6 *)&ia6->ia_addr)->sin6_addr),
460 	    &ip->ip_src, sizeof(ip->ip_src));
461 	bcopy(&in4, &ip->ip_dst, sizeof(ip->ip_dst));
462 	ip->ip_p = IPPROTO_IPV6;
463 	ip->ip_ttl = ip_stf_ttl;
464 	ip->ip_len = m->m_pkthdr.len;	/*host order*/
465 	if (ifp->if_flags & IFF_LINK1)
466 		ip_ecn_ingress(ECN_ALLOWED, &ip->ip_tos, &tos);
467 	else
468 		ip_ecn_ingress(ECN_NOCARE, &ip->ip_tos, &tos);
469 
470 	dst4 = (struct sockaddr_in *)&sc->sc_ro.ro_dst;
471 	if (dst4->sin_family != AF_INET ||
472 	    bcmp(&dst4->sin_addr, &ip->ip_dst, sizeof(ip->ip_dst)) != 0) {
473 		/* cache route doesn't match */
474 		dst4->sin_family = AF_INET;
475 		dst4->sin_len = sizeof(struct sockaddr_in);
476 		bcopy(&ip->ip_dst, &dst4->sin_addr, sizeof(dst4->sin_addr));
477 		if (sc->sc_ro.ro_rt) {
478 			RTFREE(sc->sc_ro.ro_rt);
479 			sc->sc_ro.ro_rt = NULL;
480 		}
481 	}
482 
483 	if (sc->sc_ro.ro_rt == NULL) {
484 		rtalloc(&sc->sc_ro);
485 		if (sc->sc_ro.ro_rt == NULL) {
486 			m_freem(m);
487 			ifp->if_oerrors++;
488 			return ENETUNREACH;
489 		}
490 	}
491 
492 	ifp->if_opackets++;
493 	return ip_output(m, NULL, &sc->sc_ro, 0, NULL, NULL);
494 }
495 
496 static int
497 isrfc1918addr(in)
498 	struct in_addr *in;
499 {
500 	/*
501 	 * returns 1 if private address range:
502 	 * 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
503 	 */
504 	if ((ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
505 	    (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
506 	    (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168)
507 		return 1;
508 
509 	return 0;
510 }
511 
512 static int
513 stf_checkaddr4(sc, in, inifp)
514 	struct stf_softc *sc;
515 	struct in_addr *in;
516 	struct ifnet *inifp;	/* incoming interface */
517 {
518 	struct in_ifaddr *ia4;
519 
520 	/*
521 	 * reject packets with the following address:
522 	 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
523 	 */
524 	if (IN_MULTICAST(ntohl(in->s_addr)))
525 		return -1;
526 	switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
527 	case 0: case 127: case 255:
528 		return -1;
529 	}
530 
531 	/*
532 	 * reject packets with private address range.
533 	 * (requirement from RFC3056 section 2 1st paragraph)
534 	 */
535 	if (isrfc1918addr(in))
536 		return -1;
537 
538 	/*
539 	 * reject packets with broadcast
540 	 */
541 	for (ia4 = TAILQ_FIRST(&in_ifaddrhead);
542 	     ia4;
543 	     ia4 = TAILQ_NEXT(ia4, ia_link))
544 	{
545 		if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
546 			continue;
547 		if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr)
548 			return -1;
549 	}
550 
551 	/*
552 	 * perform ingress filter
553 	 */
554 	if (sc && (sc->sc_if.if_flags & IFF_LINK2) == 0 && inifp) {
555 		struct sockaddr_in sin;
556 		struct rtentry *rt;
557 
558 		bzero(&sin, sizeof(sin));
559 		sin.sin_family = AF_INET;
560 		sin.sin_len = sizeof(struct sockaddr_in);
561 		sin.sin_addr = *in;
562 		rt = rtalloc1((struct sockaddr *)&sin, 0, 0UL);
563 		if (!rt || rt->rt_ifp != inifp) {
564 #if 0
565 			log(LOG_WARNING, "%s: packet from 0x%x dropped "
566 			    "due to ingress filter\n", if_name(&sc->sc_if),
567 			    (u_int32_t)ntohl(sin.sin_addr.s_addr));
568 #endif
569 			if (rt)
570 				rtfree(rt);
571 			return -1;
572 		}
573 		rtfree(rt);
574 	}
575 
576 	return 0;
577 }
578 
579 static int
580 stf_checkaddr6(sc, in6, inifp)
581 	struct stf_softc *sc;
582 	struct in6_addr *in6;
583 	struct ifnet *inifp;	/* incoming interface */
584 {
585 	/*
586 	 * check 6to4 addresses
587 	 */
588 	if (IN6_IS_ADDR_6TO4(in6)) {
589 		struct in_addr in4;
590 		bcopy(GET_V4(in6), &in4, sizeof(in4));
591 		return stf_checkaddr4(sc, &in4, inifp);
592 	}
593 
594 	/*
595 	 * reject anything that look suspicious.  the test is implemented
596 	 * in ip6_input too, but we check here as well to
597 	 * (1) reject bad packets earlier, and
598 	 * (2) to be safe against future ip6_input change.
599 	 */
600 	if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
601 		return -1;
602 
603 	return 0;
604 }
605 
606 void
607 in_stf_input(m, off)
608 	struct mbuf *m;
609 	int off;
610 {
611 	int proto;
612 	struct stf_softc *sc;
613 	struct ip *ip;
614 	struct ip6_hdr *ip6;
615 	u_int8_t otos, itos;
616 	struct ifnet *ifp;
617 
618 	proto = mtod(m, struct ip *)->ip_p;
619 
620 	if (proto != IPPROTO_IPV6) {
621 		m_freem(m);
622 		return;
623 	}
624 
625 	ip = mtod(m, struct ip *);
626 
627 	sc = (struct stf_softc *)encap_getarg(m);
628 
629 	if (sc == NULL || (sc->sc_if.if_flags & IFF_UP) == 0) {
630 		m_freem(m);
631 		return;
632 	}
633 
634 	ifp = &sc->sc_if;
635 
636 #ifdef MAC
637 	mac_create_mbuf_from_ifnet(ifp, m);
638 #endif
639 
640 	/*
641 	 * perform sanity check against outer src/dst.
642 	 * for source, perform ingress filter as well.
643 	 */
644 	if (stf_checkaddr4(sc, &ip->ip_dst, NULL) < 0 ||
645 	    stf_checkaddr4(sc, &ip->ip_src, m->m_pkthdr.rcvif) < 0) {
646 		m_freem(m);
647 		return;
648 	}
649 
650 	otos = ip->ip_tos;
651 	m_adj(m, off);
652 
653 	if (m->m_len < sizeof(*ip6)) {
654 		m = m_pullup(m, sizeof(*ip6));
655 		if (!m)
656 			return;
657 	}
658 	ip6 = mtod(m, struct ip6_hdr *);
659 
660 	/*
661 	 * perform sanity check against inner src/dst.
662 	 * for source, perform ingress filter as well.
663 	 */
664 	if (stf_checkaddr6(sc, &ip6->ip6_dst, NULL) < 0 ||
665 	    stf_checkaddr6(sc, &ip6->ip6_src, m->m_pkthdr.rcvif) < 0) {
666 		m_freem(m);
667 		return;
668 	}
669 
670 	itos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
671 	if ((ifp->if_flags & IFF_LINK1) != 0)
672 		ip_ecn_egress(ECN_ALLOWED, &otos, &itos);
673 	else
674 		ip_ecn_egress(ECN_NOCARE, &otos, &itos);
675 	ip6->ip6_flow &= ~htonl(0xff << 20);
676 	ip6->ip6_flow |= htonl((u_int32_t)itos << 20);
677 
678 	m->m_pkthdr.rcvif = ifp;
679 
680 	if (ifp->if_bpf) {
681 		/*
682 		 * We need to prepend the address family as
683 		 * a four byte field.  Cons up a dummy header
684 		 * to pacify bpf.  This is safe because bpf
685 		 * will only read from the mbuf (i.e., it won't
686 		 * try to free it or keep a pointer a to it).
687 		 */
688 		struct mbuf m0;
689 		u_int32_t af = AF_INET6;
690 
691 		m0.m_next = m;
692 		m0.m_len = 4;
693 		m0.m_data = (char *)&af;
694 
695 #ifdef HAVE_OLD_BPF
696 		BPF_MTAP(ifp, &m0);
697 #else
698 		bpf_mtap(ifp->if_bpf, &m0);
699 #endif
700 	}
701 
702 	/*
703 	 * Put the packet to the network layer input queue according to the
704 	 * specified address family.
705 	 * See net/if_gif.c for possible issues with packet processing
706 	 * reorder due to extra queueing.
707 	 */
708 	ifp->if_ipackets++;
709 	ifp->if_ibytes += m->m_pkthdr.len;
710 	netisr_dispatch(NETISR_IPV6, m);
711 }
712 
713 /* ARGSUSED */
714 static void
715 stf_rtrequest(cmd, rt, info)
716 	int cmd;
717 	struct rtentry *rt;
718 	struct rt_addrinfo *info;
719 {
720 	RT_LOCK_ASSERT(rt);
721 
722 	if (rt)
723 		rt->rt_rmx.rmx_mtu = IPV6_MMTU;
724 }
725 
726 static int
727 stf_ioctl(ifp, cmd, data)
728 	struct ifnet *ifp;
729 	u_long cmd;
730 	caddr_t data;
731 {
732 	struct ifaddr *ifa;
733 	struct ifreq *ifr;
734 	struct sockaddr_in6 *sin6;
735 	struct in_addr addr;
736 	int error;
737 
738 	error = 0;
739 	switch (cmd) {
740 	case SIOCSIFADDR:
741 		ifa = (struct ifaddr *)data;
742 		if (ifa == NULL || ifa->ifa_addr->sa_family != AF_INET6) {
743 			error = EAFNOSUPPORT;
744 			break;
745 		}
746 		sin6 = (struct sockaddr_in6 *)ifa->ifa_addr;
747 		if (!IN6_IS_ADDR_6TO4(&sin6->sin6_addr)) {
748 			error = EINVAL;
749 			break;
750 		}
751 		bcopy(GET_V4(&sin6->sin6_addr), &addr, sizeof(addr));
752 		if (isrfc1918addr(&addr)) {
753 			error = EINVAL;
754 			break;
755 		}
756 
757 		ifa->ifa_rtrequest = stf_rtrequest;
758 		ifp->if_flags |= IFF_UP;
759 		break;
760 
761 	case SIOCADDMULTI:
762 	case SIOCDELMULTI:
763 		ifr = (struct ifreq *)data;
764 		if (ifr && ifr->ifr_addr.sa_family == AF_INET6)
765 			;
766 		else
767 			error = EAFNOSUPPORT;
768 		break;
769 
770 	default:
771 		error = EINVAL;
772 		break;
773 	}
774 
775 	return error;
776 }
777